The kohris peters co



(No Model.)

. Patented Jun 7, 1898.

ms uomus PETERS ca, mom-Lima. wAsumc'l'om n. a

- UNITED STATES PATENT OFFICE.

ALFRED wA'LTER STOKES, OFIONDON, ENGLAND, YASSIGNOR TO B. A.

. LISTER & oo.,- LIMITED, or DURSLEY, ENGLAND.

PlP ETTE.

SPECIFICATION forming part of Letters Patent No. 605,146, dated June 7,1898.

Application filed October 27, 1897- Serial N0. 656,565- (N0 model.)

T0 at whom it-may concern.-

BeitknownthatLALFRED WALTERSTOKES, F. O. S., F. I. 0., a subject of theQueen of Great Britain and Ireland, and'a'resident of Parkhill road,Haverstock Hill, London, England, have inventeda certain new and xuseful Pipette for Automatically Measuring off Small Quantities ofLiquid, of which the following is a specification.

The apparatus may be saidto consist of an ordinary short-nosed glasspipette, terminating at the upper limit of the chamber, which is adaptedto contain the quantity of liquid to be measured off. At this place aconical valve-seat is provided for a plug or valve to fit it. The valvehas a stem, rod, or lever for operating it by, and is by preferenceprovided with a helical or other spring for holding the valve open orshut. A

Figure 1 is a longitudinal section of one form of this pipette. Fig. .2is alikesection of another form, and Fig. 3 a pla'n section.

A, Fig. 1, is the chamber for containing the quantity of liquid to bemeasured off at one operation. In its upper part it is provided with aconical valve-seat B for the valve 0 to fit. The chamber A is cofitinuedup into a tube -D, which, surrounds the ste n E of the valve. The upperend of this stem" passes out through a cork F inthenpper end of the tubeD for guiding the stem. The tube D has at its lower end two or morelater 1 openings D The helical spring G,attache to the stem E"and thecork F, tends to pull the valve out of its seat.

F is a small vent or passage in the cork.

In Figs. 2 and 3 the valve-stemE is not surrounded by a tube, but guidedbetween forks D on a rod which proceeds from the top of the chamber'A,thestem being held up to the rodD by rubber bands 1 1. The rubber ringsI hold them elastically at a slight distance. apart topreserve the rod Dfrom k n ;el ..iheiiar ein glass- When the pipette is placed in a vesselcontaining enough liquid to. cover it, it will fill frombelow',--.the'air passing out through the lateral" openings pl, Eig. 1f.By depressing arrangement the spring may be adapted to hold the valvedown in its seat, and the stem E would then have to be raised againstthe pressure of the spring while filling and also while emptying.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. A pipette consisting of a measuringchamber, a valve-seat in the upperend thereof, a continuation above the measuring-chamber and a valve andstem guided in said continuation, for the purpose set forth.

2. A pipette consisting of a measuringchamber, a valve-seat in the upperend thereof, a continuation above the measuring-chamher, a valve andstem guided in said continuation, and means for holding said valvenormally open, for the purpose set forth.

3. A pipette consisting of a measuringchamber provided with a valve-seatin its upper part, and having an upper cylindrical continuation, a valvetherefor and a valve-stem guided in the upper end of the saidcylindrical continuation, substantially as set forth.

4. A pipette consisting of the measuringchamber A, withcontinuation-tube D having openings D and provided with valve-seat B,

the valve C with stem E, the latter guided in the upper end of the tubeD, and a spring G for holding the valve open, substantially as setforth.

ALFRED WALTER STOKES. Witnesses:

V. JENSEN, FRED C. HARRIS.

